A number of different types of location-based service applications have been developed or proposed for wireless telecommunications networks, i.e., communications networks involving at least one wireless interface between communicating devices. Generally, such applications determine or otherwise obtain location information regarding the location of a mobile unit under consideration, e.g., a wireless telephone, PDA, wireless data terminal or the like, and provide service information based on the mobile unit location. Examples of location-based service applications include E911, local service information and location-based billing applications. In E911 applications, emergency calls are routed to a selected dispatcher based on the location of origin of an emergency call. Additionally, location information may be transmitted to the dispatcher or another location to assist in the emergency response. Location-based service applications provide information regarding local services such as hotels or restaurants based on a request entered via a mobile unit. In location-based billing applications, a rate for a call placed or received by a wireless telephone is dependent on the location of the phone, e.g., whether the phone is inside or outside of a “home zone” for the subscriber proximate to the subscriber's residence, business or other defined location. Various other applications have been proposed or implemented.
Location-based service applications generally involve comparing a current (or recent) location to a location of interest, e.g., a point identified by geographical coordinates, a boundary, or a predefined service zone definition, to make a binary determination (e.g., that the mobile unit is either inside or outside of a zone under consideration), a matching determination (e.g., that the mobile unit location matches or overlaps one or more stored zone definitions) or a proximity determination (e.g., to identify the closest service provider(s)). In any case, at one or more relevant processing steps, mobile unit location information corresponding to a particular time is compared to service location information corresponding to one or more service zones, service provider locations or other stored location information. Thus, in E911 applications the mobile unit location at the time of placing an E911 call may be compared to the dispatcher coverage zones of an emergency response network. In local service information applications, the location of a mobile unit at the time of submitting, for example, a local hotel information request, may be compared to a database of hotel location information. The location of a mobile unit during a call may be used by a location-based billing application to establish billing parameters for the call.
In addition, location-based service applications generally provide service information in response to an input by a subscriber or other application user invoking the application. In the case of local service information applications, the input is generally an explicit service request entered via the mobile unit. In E911 or location-based billing applications, the location-based service application may be invoked invisibly, from the perspective of the mobile unit, upon making a call. In other cases, the input invoking the application to provide service information based on the location of the mobile unit is received from a separate application. In such applications, the service information is nonetheless provided in response to an input requesting location-based services. That is, the trigger event generally is, from the perspective of the service application, a service request.
In some cases today, multiple sources of location information are available. For example, within certain areas of existing networks, a network-based Location Determination Technology (LDT), e.g., Position Determination Equipment (PDE) or a Serving Mobile Location Center (SMLC), is available to locate mobile units. Such network-based equipment often utilize a multilateration technology, such as time difference of arrival (TDOA including E-OTD and OTDOA) or angle of arrival (AOA) to locate a unit based on signals transmitted between the mobile unit and multiple equipment sites having known locations. Some mobile units are equipped with Global Positioning System (GPS) receivers that can determine the position of the unit based on signals from satellites of the GPS constellation. In addition, location information may be available from the network itself, e.g., information that is used to route calls, manage cell-to-cell handoff or otherwise operate the network. For example, such information may include a cell, cell sector or other network subdivision identifier (“Cell ID”) or handoff information residing in the network for the purposes of handoff management such as Network Measurement Report (NMR) and Mobile Assisted Hand-Off (MAHO) information. Thus, the available sources of location information may include LDT sources such as network-based LDTs and GPS and internal network information such as Cell ID and handoff information.